1. Field of the Invention
This invention relates to liners for prosthetic dental fixtures and to a method for producing such fixtures.
Difficulties are frequently reported by the dental profession in the permanent fitting of dental fixtures to patients. These difficulties include the failure of the oral bone structure to retain its original form after removal of natural teeth and the sensitivity of the mouth tissue to the pressure contact of artificial dental fixtures. An additional difficulty involves the build up of tartar and plaque on the surfaces of such fixtures with the attendant adverse effects due to the uneven surface produced by such buildups. The retention of bacteria in such buildups also has adverse affects.
These problems have been addressed by those persons working in the dental prosthesis art. Various attempts have been made to construct dental fixture liners having the following characteristics: (1) insolubility in the mouth environment, (2) adhesion to the denture fixture base, (3) permanent softness and resiliency, (4) low water absorption, (5) insignificant dimensional change during liner fabrication, (6) ease of cleaning with abrasion resistance, (7) color stability, and (8) satisfactory tissue tolerance.
2. Prior Art
The prior art has attempted to provide a suitable solution to the problem of dental fixture fit and acceptability. Various soft and elastic materials have been proposed to be used as dental fixture liners, such as natural and silicone rubbers, highly plasticized polyvinylchloride, gutta percha, butylmethacrylate polymers, polymers of esters derived from methacrylic acid, acrylic acid and higher aliphatic alcohols, crosslinked polymers of glycol-acrylates, glycol-methacrylates, and polyurethanes. However, none of these materials have had satisfactory, long-term achievement of the above-listed criteria.
In U.S. Pat. No. 3,251,910, Barnhart, a silicone rubber denture liner is disclosed. U.S. Pat. No. 3,886,659, Reifke, teaches the use of a multi-pocketed denture liner of rubber or plastic. In U.S. Pat. No. 3,889,374, Saffir, a dental liner of methyl methacrylate resin is disposed on a fluorinated resin base. This patent teaches the use of organic backbone, fluorinated polymers only; and these are used as the base material with the specific attempt to avoid tissue bearing contact. U.S. Pat. No. 4,024,636, Colpitts, discloses a denture of hard polyurethane with a soft polyurethane liner. Other patents of general interest include U.S. Pat. Nos. 554,740, Spyer; 1,917,902, Rowe; 2,457,114, Amenta, 2,888,746, Levy; 2,899,712, Smith; 3,589,010, Taniguchi, 3,628,988, Stol; 3,826,002, Faust; and 4,050,156, Chasanoff.